PV Panels on 45 degrees slope roof, torque related question

10-17-2017, 10:59 PM

Hello Everyone,

RE: solar panels 265Wt, about 65-39 inches size.

Before writing my question here I went through this forum and researched the Internet but could not find an answer, even something close. So I decided to ask those, who already have experience with solar panels installations and have knowledge in this field.

I am installing four solar panels on a roof (the very first time, am doing it for myself). This is a small cottage building with quite steep slope roof (45 degrees angle). I already set the panels on the roof and torque end and mid clamps as per specification to 10 ft-lbs.

Here is my concern and subsequent question... I am full of doubts (( In a one hand, It seems like I can torque them more without damaging PV panel frames but in the other hand I went through many online resources and most of them clearly recommend 10 ft-lbs torque saying that this is important do not torque it more than that.

Am I worry too much and 10 ft-lbs torque is enough to hold the panels? But panels are heavy enough, they are on 45 degrees slope roof (that means only friction power holds them on place), temperature fluctuation expected (I am in Canada with cold winter, a lot of snow and hot summer). If you have experience with similar installations could you please share your experience?
I really appreciate any information that can help to solve my doubts or lead me to the proper solution.

Comment

Correct, I am using racking and clamps. The installation spec tells to torque it to 10 ft-lbs. I just doubtful that panels can be really securely held with such torque at 45 degrees angle. I have no particular reasons for my doubts except feeling and no previous experience. I do not want a panel to fall on somebody's head... That's why I am asking those who has real-life experience with such installations.

Comment

Correct, I am using racking and clamps. The installation spec tells to torque it to 10 ft-lbs. I just doubtful that panels can be really securely held with such torque at 45 degrees angle. I have no particular reasons for my doubts except feeling and no previous experience. I do not want a panel to fall on somebody's head... That's why I am asking those who has real-life experience with such installations.

The IronRidge assembly uses only 80 in-lbs (6.7 ft lbs), consistent with the generally recommended torque for any 1/4" stainless bolt. That is what I've used. Follow the manual, and it won't fall on someone's head.

Comment

Am I worry too much and 10 ft-lbs torque is enough to hold the panels? But panels are heavy enough, they are on 45 degrees slope roof (that means only friction power holds them on place),

With the clamps I used they had an integrated grounding, and that meant it had little spikes that dug into the aluminum of the frames. So it wasn't just friction - the clamp was actually slightly embedded into the frame and the rail.

10 ft-lbs of torque sounds small - but it's a fair amount - and it is probably sufficient that you could hold the modules vertically. 10 ft-lbs probably means hundreds of pounds of clamping force. (One place I looked, it'll be well over 1000 lbs of clamping force)

I agree with sensij - follow the manual. They've done the engineering and figured out what will work with plenty of safety factor.